There is a paucity of information on late life bipolar disorder. Unlike bipolar disorder in the young, familial factors are less important in the elderly. In fact, available data suggests that elderly bipolar patients are a distinct group. Vascular factors may be of more importance than genetic factors in the development of bipolar disorder in late life. The present proposal is designed to compare neuroanatomical and clinical features of late life bipolar disorder to young bipolar subjects. In addition, we will contrast late life bipolar patients to similar age controls and to late life unipolar subjects drawn from our Clinical Research Center for Depression in the Elderly. This research is likely to be valuable in developing an understanding of the psychobiology of bipolar disorder and could lead to improving diagnosis and management of late life bipolar disorder.